1. Field of the Invention
The invention relates to an improvement of a wrap film containing box widely used in ordinary homes, or the like. More particularly, the invention is directed to a wrap film containing box that allows a serrated member to be removed safely and easily at the time of scrapping the box without impairing the cutting function during use, as well as a method of manufacturing such wrap film containing box.
2. Description of the Related Art
A conventional rectangular wrap film containing box is essentially made up of such components as a front plate 1, a bottom plate 2, a rear plate 3, a top plate 4, lateral plates 8, a cover strip 5, extending in such a direction as to cover the front plate 1 from the top plate 4, and lateral cover strips 11 extending in such a direction as to cover the lateral plates 8 as shown in FIG. 2(A) and FIG. 2(B) (e.g., Unexamined Japanese Utility Model Publication No. Sho. 59-28022). Most boxes of this type are made of a cardboard, and are assembled, as shown in FIG. 2(A) by folding a specially prepared unassembled cardboard such as shown in FIGS. 3(A) and 3(B) substantially at right angles to one another along dotted lines to form the surfaces of the above-mentioned component plates and by accommodating therein a wrap film R prepared by rolling a film. At the time of using the wrap film, an opening strip 6 fixed at locally bonded portions 9 is torn off along a cutting line 10 to open the box as shown in FIG. 2(A); a desired wrap film portion F is paid off from the rolled wrap film R; and such paid-off film portion F is cut away by a serrated member K made of a metal and fixed onto the box body.
In the containing box of this type, the metal serrated member is located at various positions. Generally, the serrated member is arranged either in the vicinity of the ridgeline between the bottom plate 2 and the front plate 1, at the upper edge portion of the front plate 1, or at the lower edge portion of the cover strip 5 so that the teeth of the serrated member are projected from the edge portion. Each tooth, used as the cutting tool, takes various forms. In terms of the general shape depicted by a phantom line connecting respective cutting points, the serrated members are linear, concavely arcuate, convexly arcuate, V-projected, trapezoidal, and the like. FIGS. 2(A) and 2(B) show an example in which a metal serrated member K that is linear in terms of connecting the respective cutting points with a phantom line is arranged on a lower end of the cover strip 5 (as viewed from FIGS. 2(A) and 2(B)), the lower end being of a linear shape, and in which the lateral cover strips 11 extending in such a direction as to cover the lateral plates 8 from the top plate 4 are provided to reinforce the cover strip 5.
The metal serrated member K is generally mounted on a predetermined surface of the unassembled cardboard as shown in FIG. 3(A) and FIG. 3(B). In the case of, e.g., FIG. 3(A), a long metal thin plate of uniform width, which is rolled, is paid off from the head end thereof by a predetermined small distance to be sequentially cut and serrated the paid-off metal thin plate portions using a mold, and simultaneously therewith, each cut metal thin plate portion is slit in the longitudinal direction thereof. The slits are raised to form fastening claws 12. As a result, the metal serrated members having the fastening claws are prepared. Flat cardboards, each of which is to be formed into a wrap film containing box and is prepared in advance, are supplied facedown; the fastening claws 12 are inserted into the cardboard, at which a part of the teeth of the serrated member K are projected to the opening strip 6 side from the lower end of the cover strip 5, by biasing the metal serrated member K with the fastening claws 12; and the inserted fastening claws 12 are then fastened while bent flat. As a result, the preparation of an unassembled cardboard with the metal serrated member has been completed.
One of market needs for boxes of this type is that the metal serrated member can be removed safely and easily when the box is disposed of as a waste box. For example, (1) Unexamined Japanese Utility Model Publication No. Sho. 60-195735 proposes a containing box in which a small strip serving as a tab is interposed between a lateral end of the serrated member and a predetermined cardboard portion of the box body, so that the serrated member can be stripped off easily by tearing up the end of the serrated member with this small strip; (2) Unexamined Japanese Utility Model Publication No. Hei. 4-32923 proposes a containing box in which a lateral end of the serrated member is extended and bent on the lateral plate of the box body, so that the serrated member can be torn off easily with the bent, extended lateral end as a tab; (3) Unexamined Japanese Utility Model Publications Nos. Hei. 4-62619 and Hei. 4-48120 propose a containing box in which perforations are bored in a predetermined cardboard portion having the serrated member in such a manner as to enclose the serrated member, so that the serrated member can be removed together with the predetermined cardboard portion while torn off along the perforations at the time the containing box is destroyed; and (4) Examined Japanese Utility Model Publication No. Hei. 2-37707 discloses a structural body in which a plastic film sheet that is as long as the serrated member is interposed between the serrated member and a predetermined cardboard portion of the box body and fastened.
Because of no relation with the invention, the disclosure (4) will be herein described. Such disclosure (4) is closest to the invention in terms of structural body. The plastic film sheet used in disclosure (4) is a "support" for covering the pointed teeth, and is wider than the serrated member while "projected from the teeth of the serrated member in the form of a band." Since the plastic film sheet does not have the role of tearing off the serrated member, there is no "portion projected" from the lateral ends of the serrated member in disclosure (4). Further, in disclosure (4), there is no idea teaching the tearing off of the serrated member, nor is a recitation suggesting the manufacturing method of such invention. No one can manufacture the containing box of the disclosure (4) by using the manufacture method of the present invention.
However, even though the containing boxes according to proposals (1) and (2) are easy to tear off the serrated member up to the fastened portion close to where the small strip is interposed, or up to the fastened portion close to where the tab is arranged, once the distance between the tab and the fastened portion a user wishes to tear off becomes long, the serrated member, itself is forced to be bent at the base of the fastening claw, making the tearing operation thereafter hard. If the serrated member under such condition is torn off at a stroke by force, the serrated member portion torn off in bent form springs back to the hand of the user, placing the users' hand in danger of injury. That is, it is assumed that proposals (1) and (2) consist with require the user to hold the serrated member, itself, by hand and that to tear the serrated member off piecemeal by making the tearing distance to the fastened portion short; i.e., he repeats the tearing operation by repeating his holding of the serrated member many times. Whether directly or indirectly, the condition that the user holds the serrated member, itself, by hand and repeat the holding of the serrated member, many times, may cause injury to his hand by the pointed teeth of the serrated member or the fastening claws being torn off.
On the other hand, proposal (3) addresses the problem but is not practical because the design of proposal (3) impairs the cutting performance because the perforations enclosing the serrated member reduce the rigidity and strength of the cardboard portion on which the serrated member is mounted. Such a problem will be explain with reference to the case of cutting a film in a containing box shown in FIG. 2(B) as follows. The portion of the film about to be paid-off is held while interposed between the front plate 1 and the cover strip 5, whereas the paid-off film end is pulled-out while held by hand, in such a direction as to be bent at an acute angle and abutted against the pointed teeth arranged on the lower end of the cover strip 5. With tension applied to the film under this condition, both the film and the box body are rotated in vertically opposite directions. As a result, the film is abutted against the pointed teethans is cut, by force, in such a manner as to sequentially bite into the sharp teeth of the serrated member from one lateral end to the other. While the cover strip 5, in this case, receives not only a biasing force in the vertical direction from the pointed teeth, but also, a stress in such a direction as to pull the cover strip 5 outward by pulling the pointed teeth at the same time, the cover strip is subjected to a deformation frontwardly. However, as the cardboard portion is weakened by perforations, particularly, by forming a long line of perforations along the serrated member on the cover strip, such deformation frontwardly is added to the above-mentioned deformation of the cover strip caused during the film cutting operation. Because such bending deformation reduces chances of the cutting edges abutting against the film surface at right angles to one another, the cutting performance of the serrated member is reduced. The chance of the cardboard portion being bent, in this way, increases with increasing number of film cutting operations, resulting in the user being unable to cut the film with the largely bent serrated member. On the other hand, modifying the perforations so not to cause the above-mentioned bending deformation, makes the removal of the serrated member, by cutting out the cardboard portion, difficult.
Moreover, the containing boxes of this type have, generally, been developed as mass consumption products to be supplied at low price. Thus, all the box manufacturing processes, including the printing and punching of unassembled cardboards, the forming and mounting of serrated members, as well as the assembling of containing boxes, have been designed to be very quick and automatically continuous. Consequently, any proposals must be technically practicable in terms of their being incorporated into the above-mentioned high-speed, automatically continuous manufacturing containing box line, as well as applicable with only minor modifications of the existing equipment.